Validation of a single concentration methacholine inhalation provocation test (SCIPT) in children

Sensitization to storage proteins in peanut and hazelnut is associated with higher levels of inflammatory markers in asthma

Background

Sensitization to peanuts and hazelnuts is common among young asthmatics and can be primary or a result of cross-reactivity. Sensitization as a result of cross-reactivity to birch pollen is typically associated to tolerance or mild and local symptoms upon intake of peanut or hazelnut.

Aim

The aim of this study was to investigate relationships between IgE antibody responses against peanut and hazelnut components, airway and systemic inflammation markers, lung function parameters and reported food hypersensitivity in a cohort of asthmatic children and young adults.

Methods

A population of 408 asthmatic individuals aged 10-35 years were investigated. Information on hypersensitivity symptoms upon intake of peanut or hazelnut were recorded in a standardized questionnaire. Fraction of exhaled nitric oxide (FeNO), blood eosinophil count (B-Eos), spirometry, methacholine challenge outcome and IgE antibodies to peanut and hazelnut allergens were measured by standard clinical and laboratory methods.

Results

Subjects sensitized to any of the peanut (Ara h 1, 2 or 3) or hazelnut (Cor a 9 or 14) storage proteins were significantly younger (17.6 vs 21.2 years), had higher levels of FeNO (23.2 vs 16.7 ppb) and B-Eos (340 vs 170 cells/mcl) than those displaying only pollen-related cross-reactive sensitization. Levels of FeNO correlated with levels of IgE to storage proteins in children, but not in adults. Levels of B-Eos correlated with levels of IgE to all allergen components investigated in children, but only to levels of IgE to storage proteins in adults. Anaphylaxis and skin reactions upon intake of peanuts or hazelnuts were more often reported among subjects sensitized to the respective storage proteins than among those with only pollen-related cross-reactive sensitization. As compared to peanut, hazelnut was more often reported to cause gastrointestinal symptoms and less often oral cavity symptoms.

Conclusions

Sensitization to peanut and hazelnut storage proteins was associated with higher levels of inflammation markers and food hypersensitivity symptoms in this population of subjects with asthma.

Methacholine challenge test: Comparison of tidal breathing and dosimeter methods in children

INTRODUCTION

Methacholine Challenge Test (MCT) is used to confirm, assess the severity and/or rule out asthma. Two MCT methods are described as equivalent by the American Thoracic Society (ATS), the tidal breathing and the dosimeter methods. However, the majority of adult studies suggest that individuals with asthma do not react at the same PC₂₀ between the two methods. Additionally, the nebulizers used are no longer available and studies suggest current nebulizers are not equivalent to these. Our study investigates the difference in positive MCT tests between three methods in a pediatric population.

METHODS

A retrospective, chart review of all MCT performed with spirometry at the Montreal Children's Hospital from January 2006 to March 2016. A comparison of the percentage positive MCT tests with three methods, tidal breathing, APS dosimeter and dose adjusted DA-dosimeter, was performed at different cutoff points up to 8 mg/mL.

RESULTS

A total of 747 subjects performed the tidal breathing method, 920 subjects the APS dosimeter method, and 200 subjects the DA-dosimeter method. At a PC₂₀ cutoff ≤4 mg/mL, the percentage positive MCT was significantly higher using the tidal breathing method (76.3%) compared to the APS dosimeter (45.1%) and DA-dosimeter (65%) methods (P < 0.0001).

CONCLUSION

The choice of nebulizer and technique significantly impacts the rate of positivity when using MCT to diagnose and assess asthma. Lack of direct comparison of techniques within the same individuals and clinical assessment should be addressed in future studies to standardize MCT methodology in children.

Comprehensive evaluation of airway involvement in pulmonary sarcoidosis

IOS can predict airway hyperresponsiveness and long-term outcome in patients with pulmonary sarcoidosis http://ow.ly/bkQH307VD4m.

Provocative dose of methacholine causing a 20% drop in FEV1 should be used to interpret methacholine challenge tests with modern nebulizers

RATIONALE

The American Thoracic Society guidelines (1999) for methacholine challenge tests (MCTs) using the 2-minute tidal breathing protocol were developed for the now-obsolete English-Wright (EW) nebulizer. In addition, the guideline recommendation to use the provocative concentration of methacholine causing a 20% drop in FEV1 (PC20) rather than the provocative dose of methacholine causing a 20% drop in FEV1 (PD20) for determining the level of bronchial hyperresponsiveness has been challenged.

OBJECTIVES

To determine if cumulative dose or concentration of methacholine delivered to the airways is the determinant for airway responsiveness and to validate use of the AeroEclipse* II BAN (Aero; Trudell Medical International, London, ON, Canada) nebulizer compared with use of the reference standard EW nebulizer.

METHODS

Subjects with asthma (10-18 yr old) participated in randomized, controlled cross-over experiments comparing four MCT protocols using standard methacholine concentrations, but varying: (1) methacholine starting concentration (testing for cumulative effect); (2) nebulizer (EW versus Aero); and (3) inhalation time. PD20 was calculated using nebulizer output rate, inhalation time, and preceding doses delivered. ANOVA analyses were used to compare geometric means of PC20 and PD20 between protocols.

RESULTS

A total of 32 subjects (17 male) participated. PC20 differed when starting concentration varied (0.46 vs. 0.80 mg/ml; P<0.0001), whereas PD20 did not (0.06 vs. 0.08 mg). PC20 differed with the EW versus the Aero nebulzer with 30-second inhalation (1.19 vs. 0.43 mg/ml; P=0.0006) and the EW versus the Aero nebulizer with 20-second inhalation (1.91 vs. 0.89 mg/ml; P=0.0027), whereas PD20 did not (0.07 vs. 0.06 mg and 0.11 vs. 0.09 mg, respectively).

CONCLUSIONS

In MCTs, the cumulative dose (PD20), not the PC20, determines bronchial responsiveness. Modern nebulizers may be used for the test if clinical interpretation is based on PD20. Clinical trial registered with www.clinicaltrials.gov (NCT01288482).

High levels of physical activity are associated with poorer asthma control in young females but not in males

BACKGROUND AND OBJECTIVE

Earlier studies on the levels of physical activity in asthma patients compared with controls have yielded varying results. We have previously reported that high versus moderate levels of physical activity were associated with higher prevalence of wheezing, especially in females. Here we studied the levels of physical activity in young patients with asthma and healthy subjects and their effect on asthma control.

METHODS

Four hundred eight physician-diagnosed patients with asthma and 118 controls (10-34 years) answered questions concerning frequency and/or duration of physical activity and undertook the Asthma Control Test (ACT), spirometry, methacholine challenges and exhaled nitric oxide measurements.

RESULTS

Asthma patients were more frequently physically active (P = 0.01) and for longer durations (P = 0.002) than controls. Highly versus moderately physically active patients with asthma had a higher prevalence of not well-controlled asthma (ACT < 20) when physical activity was assessed by frequency (40.6% vs 24.1%, P = 0.001) or duration (39.0% vs 21.7%, P < 0.001). This was only seen in females who had reduced ACT items (P < 0.05). Frequently versus moderately active females had an odds ratio of 4.81 (2.43, 9.51) to have ACT < 20, while no such effect was found in males (OR 1.18 (0.61, 2.30)) and this interaction was statistically significantly associated with gender (P = 0.003). No differences in fraction of exhaled nitric oxide or methacholine reactivity were found between moderately and highly physically active females with asthma.

CONCLUSION

Young asthma patients were more active than controls. High levels of physical activity were associated with poor asthma control as judged by the ACT in females, but not in males, and this appears unrelated to airway inflammation or responsiveness.

Perceived food hypersensitivity relates to poor asthma control and quality of life in young non-atopic asthmatics

Background

The relationship between perceived food hypersensitivity in asthmatics, food allergen sensitization, asthma control and asthma-related quality of life has not been studied.

Objective

Our aim was to study the prevalence of perceived food hypersensitivity in a cohort of young asthmatics, its relation to food allergen sensitization, and any correlation to asthma control and asthma-related quality of life.

Methods

Perceived food hypersensitivity, as well as IgE sensitization to common food allergens, levels of exhaled nitric oxide (FeNO), and blood eosinophil counts (B-Eos) were assessed in 408 subjects (211 women) with asthma, aged (mean ± SEM) 20.4 ± 0.3 years. Subjects filled out the Asthma Control Test (ACT) and the Mini Asthma Quality of Life Questionnaire (Mini-AQLQ). Inflammation was assessed by means of FeNO and B-Eos.

Results

Fifty-three per cent of subjects reported food hypersensitivity. A corresponding food allergen sensitization was found in 68% of these subjects. Non-atopic subjects with perceived food hypersensitivity (n = 31) had lower ACT (19 (15 - 22) vs. 21 (20 - 23), p < 0.001) and Mini-AQLQ -scores (5.3 (4.3 - 6.1) vs. 6.1 (5.5 - 6.5), p < 0.001) than subjects with no food hypersensitivity (n = 190), despite lower levels of FeNO and B-Eos (p < 0.05).

Conclusions and Clinical Relevance

Food hypersensitivity was commonly reported among young asthmatics. In a majority of cases, a corresponding food allergen sensitization was found. A novel and clinically important finding was that non-atopic subjects with perceived food hypersensitivity were characterized by poorer asthma control and asthma-related quality of life.

Bronchial hyperresponsiveness and asthma in the paediatric population

OBJECTIVE

To determine whether the intensity of bronchial hyperresponsiveness (BHR) is correlated to other clinical data such as patient age at the onset of asthma, the serum IgE levels and familial genetic susceptibility, with the purpose of establishing a prognosis or phenotype.

MATERIAL AND METHODS

BHR was evaluated using the methacholine provocation test, with the patients divided into six groups according to the amount of methacholine needed to obtain PD20. A total of 138 children and adolescents up to age 18 years (94 males and 44 females) were included. Most had a clinical diagnosis of asthma, while tracheobronchitis or rhinitis was diagnosed among the least reactive subjects. The patients were divided into subjects with a family history of atopic disease (84 cases) and those without such a history (54 cases). In this latter case we discuss possible causes of BHR or dyspnoea triggering factors.

RESULTS

There were no significant differences in patient age at onset or in serum IgE among the patients with different intensities of BHR, or between those with a family history of atopic disease and those without.

CONCLUSIONS

No differences were found among the groups. It is therefore concluded that the intensity of BHR is not a valid parameter for establishing a prognosis or phenotype, although it can be used to assess the severity of asthma.

Nasal nitric oxide is associated with exhaled NO, bronchial responsiveness and poor asthma control

The fraction of exhaled nitric oxide (FeNO) is an established marker of airway inflammation in asthma. Nasal nitric oxide (nNO) has initially been regarded as a promising marker of inflammation of nasal mucosa. However, due to its dual origins, paranasal sinuses and nasal mucosa, the clinical use of nNO is controversial. There is an inflammatory link between inflammation in the upper and lower airways within the united airways' paradigm, but the study of the clinical value of nNO in asthma has been limited. The objective of this study is to analyse nNO in asthmatics and its relationship to FeNO, bronchial hyperresponsiveness, allergic sensitization and asthma control. A total of 371 children and young adults from an asthma cohort were included in this study, which performed measurements of nNO (through aspiration at 5 mL s(-1)), FeNO, bronchial responsiveness to methacholine, blood eosinophil count (B-Eos) and IgE sensitization. The asthma control test (ACT) and a questionnaire regarding medical treatment, symptoms of asthma, rhinitis and chronic rhinosinusitis were completed by all subjects. An association was found between higher nNO levels and increased bronchial responsiveness (p < 0.001), FeNO (p < 0.001) and B-Eos (p = 0.002). Sensitization to furry animals related to higher levels of nNO (p < 0.001). Subjects with poorly controlled asthma (ACT < 15) had lower levels of nNO than subjects with a higher ACT score (619 ± 278 ppb, versus 807 ± 274 ppb, p = 0.002). Loss of smell showed the strongest association with lower nNO levels among the upper airway symptoms recorded. In patients with asthma, nNO was positively correlated with exhaled NO, bronchial responsiveness and asthma control. This study suggests clinical utility of nNO in subjects with asthma, but in order to get better understanding of the nNO determinants, simultaneous mapping of upper airway comorbidities by clinical examination is appropriate.

Aeroallergen and food IgE sensitization and local and systemic inflammation in asthma

BACKGROUND

We recently reported an independent association between IgE sensitization to food allergens and increased airway inflammation, assessed by fraction of exhaled nitric oxide (FeNO), in a population-based study (J Allergy Clin Immunol, 130, 2012, 397). Similar studies have not been performed in populations with asthma. The aim of the present study was to investigate the allergic sensitization profile in asthmatics and examine FeNO, airway responsiveness and blood eosinophilia in relation to type and degree of IgE sensitization.

METHOD

FeNO, airway responsiveness, blood eosinophil count (B-Eos) and IgE sensitization to food allergens and aeroallergens were determined in 408 subjects with asthma, aged 10-34 years.

RESULTS

Asthmatics had higher prevalence of IgE sensitization against all allergens than controls (P < 0.001). Mite, pollen, furry animal, mould and food sensitizations were each associated with increased FeNO, airway responsiveness and B-Eos in asthmatics. IgE sensitization to mould, furry animals and food allergens was independently related to FeNO (all P < 0.05) after adjustment for age, sex, height, smoking history and medication. IgE sensitization to mould (P < 0.001) and furry animals (P = 0.02) was related to airway responsiveness in a similar model. Finally, IgE sensitization to mould (P = 0.001), furry animals (P < 0.001) and food allergens (P < 0.001) was independently related to B-Eos.

CONCLUSION

Independent effects of IgE sensitization to aeroallergens (furry animals and mould) and food allergens were found on both local and systemic markers of inflammation in asthma. The finding regarding food IgE sensitization is novel, and a clinical implication might be that even food sensitization must be assessed to fully understand inflammation patterns in asthma.

The interest of FEF(25-75) in evaluating bronchial hyperresponsiveness with the methacholine test

BACKGROUND

Bronchial hyperresponsiveness is the pathogenic basis of asthma, and measurement of its intensity is investigated using the methacholine provocation test, which not only and particularly evaluates the reduction in FEV1 (PD20) but also takes forced mid-expiratory flow or FEF(25-75) (PD40) into account. The present study aims to evaluate the usefulness of both parameters.

MATERIAL AND METHODS

Provocation testing was carried out in 151 patients between 7 and 22 years of age diagnosed with asthma, tracheobronchitis and/or rhinitis, using a short method that allows quantification of the methacholine administered. The subjects were divided into three groups according to the amount of methacholine needed to obtain the mentioned parameters (group 1: ≤1000μg; group 2: 1001-2000μg; group 3: ≥2001μg).

RESULTS

Greater variability was recorded for FEF(25-75) than for FEV1. Paired comparison among the three groups for FEV1 proved significant, in the same way as for FEF(25-75) between groups 2 and 3, and 1 and 3, but not between groups 1 and 2. Calculation was made of the amount of methacholine required to obtain PD20 and PD40 from the same dose. Only the significant differences corresponded to the comparison of group 1 versus the rest, with no differences between the means of the total mean values.

CONCLUSIONS

The utility of PD20 is more evident, considering the variability of PD40; the latter may be useful in patients with rhinitis or tracheobronchitis when PD20 proves scantly demonstrative.

Methacholine challenge--comparison of an ATS protocol to a new rapid single concentration technique

Bronchial methacholine challenge is well established in asthma diagnostics and research. ATS guidelines propose a five step standard dosimeter (SDM) protocol with incremental concentrations of methacholine to calculate the concentration causing a 20% drop in FEV(1) in an individual (PC(20)FEV(1)). In contrast, the aerosol provocation system (APS) by Viasys automatically determines the administered dose of methacholine by measuring the effective nebulisation time and referring it to drug concentration and nebuliser power. Therefore, it offers a feasible and less time-consuming provocation procedure by applying incremental doses (PD(20)) of methacholine using a single concentration (16mg/mL methacholine, APS-SC). In this study we compared these two methods in 52 young adults (25+/-5.8 years). Following a screening visit, subjects were randomly assigned to undergo either SDM or APS-SC followed by the other method within 1 week. A close correlation between concentration and dosage causing a 20% fall of FEV(1) was found (r=0.69, p<0.001). Using the ATS categorisation of bronchial responsiveness we interpreted the results of the APS-SC method as follows: PD(20) methacholine<0.3mg as "moderate to severe BHR", 0.3 - 0.6mg as "mild BHR", 0.6 - 1.0mg as "borderline BHR", and>1.0mg as "normal bronchial response". We conclude that the five-step APS-SC is a suitable method, providing reliable results. In clinical practice the APS-SC is a timesaving procedure and less prone to errors since only one dilution of methacholine is necessary compared to the SDM.

Limitations of questioning asthma to assess asthma control in general practice

BACKGROUND

The monitoring of children with asthma in primary care is based on the occurrence and frequency of asthma symptoms. We questioned whether the current approach is adequate to identify all children in whom a sufficient level of asthma control is not achieved.

AIM

The aim of this study is to illustrate that in some children asthma was incorrectly considered controlled, because the children failed to report current symptoms of asthma.

PATIENTS AND METHODS

One hundred and nineteen children were identified with recent wheezing plus moderate or severe airway hyperresponsiveness. We analyzed whether these children reported current symptoms of asthma (as normally questioned during a routine visit).

RESULTS

In 20 children (18%) current asthma symptoms were absent despite moderately or severe airway hyperresponsiveness and wheezing in the last year. In addition, the usage of controller medication was very poor.

CONCLUSION

We conclude that the general practitioner has insufficient tools to adequately assess asthma control in all children. The assessment of airway hyperresponsiveness as an additional guide to manage asthma in children in general practice is recommended. In this way, better asthma control can be achieved.

Assessment of inhalation technique in children in general practice: increased risk of incorrect performance with new device

In a general practice based population 76% of 530 children inhaling asthma medication inhaled correctly. However, important differences among inhalers were found. Children with a pressurized metered-dose inhaler without a spacer device performed worst, with only 22% inhaling without essential errors. At a second evaluation of the inhaler technique, one year after the first assessment, performances with a new device were more often incorrect versus the unchanged devices (21.1% and 10.8%, respectively; p = 0.01). Providing children with a new device should be carefully controlled over time especially because these children are error prone.

Severe airway hyperresponsiveness was not predictable with the use of current tools in asthmatic children in general practice

OBJECTIVE

To evaluate whether moderate to severe airway hyperresponsiveness (AHR) could be suspected with the use of routinely available clinical and environmental information.

STUDY DESIGN AND SETTING

Cross-sectional study of asthma in 526 asthmatics aged 7-17 years and treated in general practice.

RESULTS

Moderate to severe AHR was present in 48% (n=253) of the participants. The presence of inhalation allergy, nocturnal symptoms, and usage of beta2-mimetics were significantly associated with moderate to severe AHR. If all three factors were present, the probability of the presence of moderate to severe and severe AHR was 76% and 36%, respectively. If all three were absent, the probability decreased to 11% and 5%, respectively. In 319 subjects (64%) AHR could not be adequately predicted with routinely available information.

CONCLUSION

Moderate and severe AHR could not be suspected with the use of routinely available clinical and environmental information in the majority of children. Except for a subgroup of children, our models were not helpful in deciding in which child an inhaled corticosteroid should be started or whether the dose should be increased or decreased. We recommend measuring the severity of AHR in these children by means of an inhalation challenge test.